Preparation of efficient, stable, and reusable copper-phosphotriesterase hybrid nanoflowers for biodegradation of organophosphorus pesticides

Abstract

Phosphotriesterase (PTE) is considered to be a good biodegradation agent for organophosphorus pesticides. However, the instability of the free PTE limits its application. In this study, the free PTE was hybridized with copper ions (Cu2+) to enhance its catalytic stability and activity. The acquired particles were freeze-dried after precipitation with PO43− at 4 °C for 72 h. Scanning electron microscopy showed that the Cu-PTE complexes formed flower-like nanoparticles after hybridization. The characteristic peaks of both the enzyme and metal material were revealed by Fourier transform–infrared spectroscopy. X-ray diffraction analysis indicated that PTE was encapsulated in the Cu3(PO4)2·3H2O based hybrid nanoflowers. Compared with free PTE, the catalytic activity of Cu-PTE hybrid nanoflowers was significantly increased about 2.2 fold. The catalytic efficiency (kcat/Vmax) of Cu-PTE hybrid nanoflowers was 1.76 fold than that of free PTE. The stability of the immobilized PTE under thermal and pH conditions was improved and the tolerance of it to organic solvents was also enhanced. Moreover, the Cu-PTE hybrid nanoflowers still exhibited 72.3 % relative activity after ten consecutive reactions. In general, this is the first time to use copper based hybrid nanoflowers to immobilize PTE, and the immobilized enzyme shows excellent performance on OPs degradation. The Cu-PTE hybrid nanoflowers may have great potential in the biodegradation of organophosphorus compounds in future.